1. Technical Field
Embodiments of the present disclosure relate generally to communication systems, and more specifically to techniques for detection of a transmitted signal (vector) in multiple-input multiple-output (MIMO) communication systems, using Monte Carlo sampling techniques.
2. Related Art
Multiple-input multiple-output (MIMO) communication systems (MIMO systems) are well known in relevant arts, and generally refer to systems in which multiple antennas are employed for communication between a transmitting device (MIMO transmitter) and a receiving device (MIMO receiver). The transmitting device may either represent a single device with the multiple antennas, or multiple (separate) devices, each with its own antenna(s). MIMO technology is currently utilized in wireless communication according to standards such as, for example, IEEE 802.11n, 802.11ac, LTE-Advanced, WiMAX, etc. Each of the multiple separate MIMO transmitters may represent a different user. For example, assuming there are Nt different users, each having one transmit antenna, a total of Nt symbols are transmitted simultaneously in each “symbol period”, one symbol from each of the Nt users. One of several modulation techniques may be used to transmit each of the symbols. In addition, suitable MIMO encoding techniques may be employed in the MIMO transmitter to generate the symbols after modulation.
A corresponding MIMO receiver with Nr receive antennas (Nr being equal to, or different from (typically larger than) Nt) may receive, on each of the Nr antennas, a superposition of the Nt symbols altered by the wireless channel during propagation from the transmitter(s) to the receiver. Detection (or estimation) refers to determination/estimation, at the MIMO receiver, of the values of each of the Nt transmitted symbols in each symbol period.
MIMO systems that employ large number of antennas (for example, to achieve high data transmission rates, throughputs), the process of detection may be associated with correspondingly high computational complexity. Another concern with detection techniques in a MIMO receiver may relate to performance (or reliability). In general, the detection needs to determine (or estimate) the transmitted symbols accurately, preferably close to optimum bit-error rate (BER) performance. In general, a lower BER corresponds to a better performance of the detection techniques, and vice-versa.
Markov Chain Monte Carlo (MCMC) sampling techniques have previously been employed in a MIMO receiver for the estimation of the multiple (Nt) transmitted symbols. However, simple MCMC sampling techniques employing Gibbs sampling may be associated with a potential drawback generally termed “stalling” that may occur at high receive signal-to-noise ratio (SNR). Stalling occurs when the iterations of the MCMC technique repeatedly generate the same candidate vector (constructed from the transmitted symbol alphabet) as a next potential solution vector, such that the estimation may ‘stall’, i.e., does not progress further.
Several features of the present invention provide a MIMO signal estimation technique employing MCMC techniques that obviates the stalling problem noted above, and provides good performance while being of sufficiently low-complexity for its implementation.